There is a plurality of communication systems in which a host device is coupled to an accessory device, wherein both devices are connected by a communication path. The host device may, for example, be configured as a mobile phone, a tablet PC or a multimedia player. The accessory device may be an earphone to play an audio signal, a display to render an image transferred to the display from the host device or a microphone to record speech data to be transferred to the host device.
Whereas in the past accessories have mostly been configured as passive devices, modern accessory devices are steadily gaining more intelligence and more independence so that they are no longer simply passive devices. Examples of such intelligent accessories are active headset, for example active noise-cancelling headsets or gaming headsets, sensor hubs, such as RFID tags and sensor devices, microphone-arrays or, for example, pico-projectors.
In mobile applications, three main connector families exist to provide an interface between accessory devices and host devices: USB connectors, 3.5 mm jack interfaces and custom connectors, for example Apple 30 pin connector. The most prolific and most used connector is the 3.5 mm jack interface (plug and socket). However, the limitation of the 3.5 mm jack is the number of connections. Three and four connections remain the mainstream. A fifth connection exists but is, however, not widely used and is not backward compatible. The standard 3.5 mm jack comprises four poles, particularly an LS1-pole to transfer audio data for a left channel, an LS2-pole to transfer audio data for a right channel, GND-pole to provide a ground connection and an AUX-pole for auxiliary connection. The AUX-pole in legacy products is often used to transmit speech microphone data and/or remote functions, such as call pickup, call drop, fast forward, fast rewind, volume up and volume down, from the accessory device to the host device.
Power to supply an accessory device provided from the 3.5 mm jack is usually limited to a few milliwatts which may be enough to bias a speech microphone in hands-free kits or power a remote control function found in certain dongles. However an intelligent accessory typically requires power in a range lower than 500 mW. The transfer of adequate power to operate intelligent accessory devices is not possible. The transfer of coded communication data with a data communication protocol between a host device and an accessory device is currently also not arranged via the auxiliary connection of the 3.5 mm jack interface. Thus, intelligent accessory solutions today require batteries to provide power and either wireless or other than 3.5 mm jack connections for communication by exchanging a bit stream comprising data words coded in a certain format.
It is desirable to provide an electrical power transmitting controller device for use in a host device to transmit electrical power to an electrical power receiving controller device of an accessory device, wherein power may be transmitted to the electrical power receiving controller device via a 3.5 mm jack interface which connects the host device and the accessory device. A further concern is to provide a host device to provide power to an accessory device wherein the host device and the accessory device are coupled by a 3.5 mm jack interface. Furthermore, it is desirable to provide an electrical power receiving controller device for use in an accessory device to receive power from an electrical power transmitting controller device of a host device, wherein the accessory device and the host device are coupled by a 3.5 mm jack interface. Furthermore, an accessory device with receiving power from a host device, wherein the accessory device and the host device may be coupled by a 3.5 mm jack interface is specified. Another concern of the present invention is to specify a communication system in which power and/or communication data may be exchanged between a host device and an accessory device coupled together by means of a 3.5 mm jack interface.